Construction machine and controls therefor

ABSTRACT

The main frame of the construction machine disclosed is supported upon two pairs of crawler tractors through a five point suspension using four hydraulic rams, two of which cooperate with one pair of tractors and two of which cooperate with the other pair of tractors through a walking beam. Each tractor is individually driven and pivotally mounted from a saddle on a vertical axis. Opposite fore and aft pairs of tractors are connected by a double steering linkage, the geometry of which is modified to increase the steering sensitivity and provide for automatic simultaneous extension and retraction of the dual linkages to accommodate maximum grade and slope deviations without affecting the level of the main frame or working tool. Cross or parallel connected extensible members are also used in the sensor linkages controlling the steering to compensate for and reduce both over-and under correction. The walking beam can be located on a side of the machine longitudinally oriented with the direction of travel or at the front or rear of the machine transverse the direction of travel. The working tool, such as a slip form or mule shoe for curbings, has automatically adjustable skirts to prevent edge slump as it traverses the grade deviations and can be extended or retracted from the side of the main frame to different work locations or relocated at the back of the machine for highway travel and trailering of the machine. The hopper and screw conveyor cooperate in pivoting to and from the work position.

United States Patent 1 Miller et al. 1 Jan. 16, 1973 [54] CONSTRUCTION MACHINE AND [57] ABSTRACT CONTROLS THEREFOR The main frame of the construction machine disclosed [75] Inventors: Charles R. Miller; Allen R. Miller, is supported upon two pairs of crawler tractors both of McHenry; David J. Miller, through a five point suspension using four hydraulic Ringwood, all of ill. rams, two of which cooperate with one pair of tractors [73] Assignee: Miller Formless Co., Inc., Mcl-ienry, and two of which P with the other i "L tractors through a walking beam. Each tractor IS individually driven and pivotally mounted from a saddle Filed! 1971 on a vertical axis. Opposite fore and aft pairs of trac- [21] APPL 3 423 tors are connected by a double steering linkage, the

geometry of which is modified to increase the steering Related Application Data sensitivity and provide for automatic simultaneous ex- [63] Continuatiommpart of Sen No 774,014, 7 tension and retraction of the dual linkages to accom- 196g, 3,606,327, modate maximum grade and slope deviations without affecting the level of the main frame or working tool.

[52] U.S. Cl. ..94/46R Cross or parallel connected extensible members are [51] Int. Cl ..E(llc 19/48 also used in the sensor linkages controlling the steer- Field Of 46 ing to compensate for and reduce both over-and under correction. The walking beam can be located on a side References Cited of the machine longitudinally oriented with the UNTED STATES PATENTS direction of travel or at the front or rear of the machine transverse the direction of travel. The work- 3,257,9l7 6/1966 Lewis ..94/46 R ing [00], ugh as a form or mule shoe for curbings 3,247,922 4/1966 Hanson ..l80/9.46 has automatically adjustable skins to prevent edge 533331332 31322 3332311311.......:::::::::1::::::3il222% Slump as it the grade deviations and be Primary Examiner-Nile C. Byers, Jr. Attorney-Harbaugh & Thomas extended or retracted from the side of the main frame to different work locations or relocated at the back of the machine for highway travel and trailering of the machine. The hopper and screw conveyor cooperate in pivoting to and from the work position.

24 Claims, 21 Drawing Figures PATENTEDJAMB ms 3.710.695

SHEET 1 UF 7 CHARLES F. M/LLER ALLE/V R. MILLER DAV/D J. M/LLER A from eys PATENTED A 16 I975 3.710.695

SHEET 2 [IF 7 ALLEN R. M/LLER DAV/D J. M/LLER fforneys PATENTEDJAH 16 1915 3.710.695

ISON O 7 lNVE/VTORS: CHARLES M/LLER ALLEN R. M/LLE'R DAV/D J. M/L L El? A Horneys PATENTEDJAN 16 I975 SHEET 5 OF 7 //V VE/VTO/PS. CHARLES E M/L LER u ii lxll ll :llll

ALLE/V R. M/LLER DAV/D J. M/LLER Attorneys PATENTEUJAN 16 I975 sum 6 OF 7 FIG. [5

r CHARLES MILLER ALLEN M/LLER DAV/D J. M/LLEI? Afforneys PATENTEDJAHSIQIS 3.710.695

SHEET 7 [1F 7 v INVENTORS; CHARLES R MILLER ALLE/V R. MILLER DAV/D J. MILLER By $0111 M YQ ZQWM A Horneys CONSTRUCTION MACHINE AND CONTROLS 5 THEREFOR RELATED APPLICATION:

This application is a continuation-in-part of application Ser. No. 774,014, filed Nov. 7, 1968 by the instant inventors now US. Pat. No. 3,606,827.

BACKGROUND OF THE INVENTION:

One of the primary problems in the art of construction machinery such as a road grader, designed to prepare a finished sub-grade or a paver designed to lay a finished concrete layer on a sub-grade, has been the accurate control of the grade and slope of the working tool. Prior to the year 1949 it wasthe practice to prepare a fairly smooth sub-grade using graders and compactors and then carefully erect steel side forms along the grade to contain the concrete layer'in the prescribed horizontal attitude. The use of side forms, still in wide use today, increases overhead, man power requirements and labor costs. The side forms must be accurately placed since the elevation of the top edges is used not only as a track for the concrete laying machine but as a grade and slope reference for the surface finishing devices that are subsequently applied by hand or by machine.

The elimination of the I use of side forms and the design of machinery to provide accurate slope and grade control has been a slowdevelopment. Employees of the Iowa State l-lighway'Commission are responsible for the introduction of slip-form paving which has now been in use on a practical basis since 1955. In the first successful machines the concrete was deposited directly on the sub-grade in front of the'machine rather than into a metering hopper, as used in the earlier experimental machines, and the width of the lane was increased to that of a two-lane pavement. Propulsion was affected through two long crawler tractors, one on. each side of the machine. These developments were significant in this art. Among theproblems encountered and overcome by these innovators were edge slump of the concrete; striking off of the concrete immediately ahead of the main screed; the use of power-driven strike-off blades to increase uniformity of level; quick adjustment of the crown of the main screed and the use of tamping bars and oscillating belt finishers along with extension of the side forms to further increase the accuracy of the level, etc. Even sothere was, and still is, ex-

tensive use of diamond bump-cutting of the hardened concrete and the problem of greatly increased over-run in concrete quantities caused by sub-grading inaccuracies. Some of these deficiencies are overcome by employing four independent track assemblies on the main frame, one at each corner and a degree of acceptable smoothness in the finished concrete was attained by employing a hand-drawn pipe float behind several forms of towed finishing devices. Both manual andautomatic controls for steering and control of the elevation and cross-slope of the screeds are used in the present day slip form frames. Dependence is placed upon the mass and length of a slip-form paver to over.- come'some of these problems. Rapid lateraldistribution of the fresh concrete by angular screw conveyors has tended to reducethe tendency of the screeds and other working tools from floating on the. changing line. The invention overcomes the problem of hunting masses of material being handled. Despite these developments the important characteristics which distinguish the slip-form method over the side form. construction are the matters of sub-grade accuracy,

concrete uniformity, reinforcing steel installation, mix.

compaction, surface finish and pavement smoothness.

' Because of the absence of a continuous elevation reference heretofore provided by the meticulously placed side forms, it is still necessary to use special techniques in constructing the sub-grade to accurate tolerances for grade and cross-section and this require ment is one of the critically important characteristics of present slip-form paving methods. Also, because of inaccuracies of the sub-grade and sluggish grade and.

slope control, means to detect and follow the depth of concrete slab being laid. are commonly used. A related and equally important characteristic is the need for an area just outside of each pavement edge which is care-- fully shaped and compacted to comparable grade tolerances in order to provide a path for the machine to travel.

Accordingly, grade and slopecontrol of the working tool on the main frame of large and small machines is and the machine can negotiate an uneven sub-grade while applying the working tool with improved accuracy to the same sub-grade or.to a parallel sub-grade under the control of asingle grade reference line whether curved or straight. The suspension and steering control of this invention can be used to improve the operation of slip-form pavers used to construct our modern highways and give the machine a capability of laying a strip of pavement. at better than acceptable tolerances in grade and slope accuracy for the completed pavement, while at the same time negotiat ing both sharp and gradual curves within unexpected tolerances dependent only on the accuracy with which I.

the single grade reference is installed. The suspension, steering and leveling control of this invention allows the machine to traverse'anuneven sub-grade while doing work upon or laying a curbing or sidewalk upon an area to the side of the sub-grade under the control of a grade reference line.

SUMMARY THE INVENTION:

The invention concerns the provision of certain changes in the geometry of the linkage means used in suspending and steering the corner-positioned ground engaging means whereby the response of the machine to the sensed changes in grade, slope or steering is tuned to and totally compatible with the sensitivity of the means used to follow the grade-slope reference and both over and under correction by the electrohydraulic steering and suspension control system and coordinates the geometry of the suspension with the power and inherent performance characteristics of the electro-hydraulic components used. Furthermore, the

level, compaction and character of the concrete strip being laid is maintained irrespective of gross and sudden changes in the weight of concrete carried or being worked on by the machine.

Briefly, the invention relates to an improved fivepoint articulated or pivotal suspension of the main frame upon four corner tractors; an improvement in the accuracy and sensitivity of the steering linkage for the fore and aft front and rear tractor pairs, by connecting the steering rams between one linkage and the other or to the saddle mount on each side of the respective steering pivots; the provision of cross-connected or parallel-connected extensible members in the steering linkage to provide the added capability of simultaneous lateral extension and automatic compensation for all slope deviations; a ski-controlled extensible skirt on the I working tool or slip form to compensate for deviations of the sub-grade at the side of the concrete slab and provision for lateral adjustment of the working tool in relation to the main frame to facilitate working from a poorly prepared sub-grade, or no grade at all, upon a sub-grade along the side of the machine. A related and cooperating cross-connected or parallel-connected extensible members in the steering sensor geometry is used to compensate for over-and-under-steer thereby enabling the machine to negotiate curves with exceptional accuracy.

In one embodiment'the machine is adapted to fold into a compact size, use the auger blade to pivot the hopper, drop the working tool, such as a slip-form and pick it up at another part of the main frame to decrease the width for highway travel. A slip form paver is provided which is 'capable'of laying a slab having grade and slope tolerances within about 0.10 inch and follows a reference line around curves with the same accuracy that the reference line is suspended from its supporting stakes, even to the extent of detecting straight line seg ments between the supporting stakes for the reference line.

DESCRIPTION OF THE DRAWINGS:

The invention is illustrated, without limitation, by the drawings showing a curb-laying machine wherein:

FIG. 1 is a perspective view showing the front and outboard or curb side of the machine of this invention;

FIG. 2 is a side elevational view of the machine illustrated in FIG. 1 showing the outboard or curb side;

FIG. 3 is an end elevational view of the back .of the machine with the curbing being laid shown in cross-section;

FIG. 4 is a cross-sectional view taken along the line 4-4 of FIG. 2 to show the four-point bogey or saddle suspension, the steering linkages, grade compensators and sensor guidance system;

FIG. Sis a fragmentary cross-sectional view to show the articulation and lateral adjustment of the material FIG. 9 is a fragmentary perspective view of the mule shoe showing one form of elevation adjustment therefor;

FIG. 10 is a cross-sectional view taken along the lines 10-10 ofFIG. 9;

FIG. 1 l is a cross-sectional view taken along the lines 11l1 ofFIG. 10;

FIG. 12 is a fragmentary perspective view of one form of grade and steering sensor mount for the front 'of the machine;

F IG.13 is a fragmentary perspective view of the sen-- sor mounting for the rear of the machine;

FIG. 14 is a fragmentary perspective view of the adjustable mount for the rear sensor;

FIG. 15 is an exploded view in partially diagrammatic form to show the lateral displacement and attaching means for the mule shoe;

FIG. 16 is a diagrammatic view to illustrate the placement of the walking beam transverse of the main frame, fore or aft, of the machine;

FIG; 17 is a simplified view of the machine to illustrate that the entire machine can be raised andlowered to lift the mule shoe to its working position or lower the mule shoe for detachment from the frame;

FIG. 18 illustrates the position of the mule shoe after- THE PREFERRED EMBODIMENT:

Referring to the drawings, particularly FIGS. 1, 2 and 3, the invention is illustrated'by the curb-forming machine 10 having the supply hopper 12 adaptedto receive concrete 14 from the chute 16 of a concrete truck (not shown), convey the concrete upwardly through the screw conveyor 18, operated by the hydraulic motor and drive unit 20 and deposit the concrete from the opening '22 into the feed hopper 24. The concrete is subjected to vibration to eliminate air bubbles in the feed hopper 24 by means of the electric v vibrators (not shown). Such vibrators are positioned eliminate air bubbles and facilitate the flow through the hopper. The consistency of the concrete is maintained so as to prevent slump of the finished curb.

Although. these, component parts 'comprising the concrete handling system. are known in' the art and represent a material handling system adapted to supply a continuous stream of material to a desired location, their structures and placement on the machine are not a matter of choice. The hopper 12 is located .on the front of the machine'with two sides of the hopper accessible over which to extend the chute 16 from the truck. The truck can fill from a side position or forward position and in full view of the operator of the curb machine in either position. The feed hopper 24 is frusto-pyramidal in shape to facilitatecompactionand has an open bottom communicating with the slip form or mule shoe 30. This member is elongated and detachably affixed to the main frame member 32 by means of the adjustable lateral support members to be described.

The hopper 12 is constructed of heavy duty sheet metal and properly supported to receive loads of concrete weighing up to 6,000 lbs. The screw conveyor 18 and the hopper 24 can contain, at any one time, an additional 2,000 to 3,000 lbs. of concrete. These loads are constantly changing as the machine progresses along the sub-grade 34 in the direction of the arrow 36. The suspension and controls of this invention are adapted to maintain the mule shoe 30 at the desired slope, grade and path of curvature irrespective of these additional forces acting on the machine, without impairment of the compaction (density) of the finished curbing, illustrated at 38, and regardless of macrodeviations in the sub-grade which may be plus or minus 6-8 inches or more, as will be described. The suspension of this invention isillustrated by means of a curblaying machine which must be compact, accurate and versatile, and also since the mule shoe is required to handle the concrete under less ideal conditions than the working tool, such as a screed, that is carried under and transversely of a long-frame road machine. The machine illustrated is capable of emptying all of the concrete therefrom in about 12 seconds. Thus, during operation, a variety of forces are acting in different magnitudes and directions upon the frame 32 and the center'of gravity is constantly shifting. Another factor is the upward pressure of the mule shoe upon its mounting with frame due to the compacting forces 4 upon the curbing being laid.

The slip form or mule shoe 30 is closed at the front end by the transverse wall member 40 through which extend the guide tubes 42 having open flaredends to easily receive the reinforcing rods (not shown). The guide tubes 42 are spaced laterally from each other and also spaced above the bottom of the slip form. Any number of tubes 42 can be used with any desired spaced configuration in the wall 40. When the tubes 42 are not in use suitable telescoping covers 44 are inserted in their openings to prevent concrete from squeezing out or foreign material from entering the slip form.

Referring briefly to FIG. 15, some of the details of the slip form 30 are shown as one embodiment of the invention. This member is elongated and has an inner uniform contour 46 throughout its length to lay any desired curb or gutter design to specifications including the so-called battered form illustrated and such other contours such as drive over, roll and vertical curbs. The slip form 30 can be any desired length and can be widened so that sidewalks can be laid. The rear end of the slip form 30 is open and the arrangement is so spaced above the grade level 34 to form or lay a continuous curb 38, with or without reinforcing rods as the machine moves in the direction of the arrow 36 (FIG. 1). The capacities of both the hoppers l2 and 24 are such that the machine can move continuously along the grade 34 and lay a continuous curbing with only intermittent interruptions for the laying of expansion points as may be required or adjustment of the concrete trucks, which move along with the machine as they discharge their loads into the hopper 12. The reinforcing rods are placed in the tubes 42 by hand as the curbing progresses.

As shown best in FIG. 15, the hopper 24 is attached to and in communication with the mule shoe 30 at the forward end, just behind the plate 40. The reinforcing girder plates 48 are provided at spaced points along the length of the mule shoe, same being contoured to fit over the outer surfaces of the mule shoe and affixed thereto by welding. The longitudinal reinforcing channel 50 is affixed at or near the lower outer edge of the mule shoe, also by welding. The mule shoe has the spaced up-rights 52 and 54 in the front, the intermediate uprights 56, with suitable rungs therebetween to form a ladder and the pair of rear uprights 58 and 60, that may be off-set rearwardly by the extensions 62, and have the uprights 64 and 66 affixed thereto. These uprights are adjustably affixed to the rectilinear platform frame 68, which has a non-skid flat grill 70 thereover.

The frame 68 has the front bracket 72 and the pair of spaced rear brackets 74 and 76 along the inner edge, for purposes to be described. In FIG. 1, his seen that the main frame member 32 is provided with a working platform 78 of non-skid expanded metal form. When the mule shoe is attached to the main frame 32, the platforms 70 and 78 are coplanar to provide a safe working area as shown in FIG. 17.

An illustrative structure of the main frame 32 is shown in FIG. 15 wherein the front and rear tubular members 80 and 82 are joined to the outboard side member 84 and the inboard side member 86 in the form of a box frame. A connecting longitudinal brace member 88-, spaced from the side members 86 provides suitable rigidity and support for the prime mover 90 (FIG. 1) which is located on that side of the main frame. The front and rear tubular cross members 80 and 82 extend slightly beyond the side member 84 with their open ends 92 in an accessible position, as desired.

A pair of elongated rigid hanger members 94 (front) and 96 (rear) is provided which have outer surfaces contoured to fit within the respective openings 92 in telescoping relationship. The front extension of the tubular frame'member 80 is provided with a threaded opening that receives the set bolt 98 and the rear extension of the rear frame member 82 has the set bolt 100 (see FIG. 5) also engaging a threaded opening. For this purpose a bore hole can be drilled into the side of these members and a nut welded over the bore hole into which the set bolts engage. More than one such set bolt can be used at these front and rear frame locations. The hanger members are provided with the tab brackets 102 and 104, respectively, with suitable bolt holes illustrated at 105 for attachment to the brackets 72 and 76 by means of bolts (not illustrated) which engage therethrough. The hangers thus rigidly and conveniently attach to the mule shoe frame 68 and extend in spaced horizontal relationship therefrom. The height of the frame 68 from the grade 34 is such that by manipulation of the hydraulic suspension in a manner to be described the mule shoe can rest upon the ground and is easily detachable. With the hangers 94 and 96 so attached to the mule shoe frame 68 they align with the openings 92 and telescope therein for locking at the desired lateral displacement from the main frame 32 by means of the easily accessible set-bolts 98 and 100.

The machine is self-contained with the prime mover 90 supplying the power necessary to drive the hydraulic. pumps, hydraulic motors and generators that are required. All functions of the machine can be controlled by one man from the platforms and 78 from which position the rate of discharge from the hopper 24 can be observed, with the control console 106 in convenient access. The top part of the panel of the console contains the controls and instruments for the prime mover and elevation and slope control system, while the lower part of the panel contains the controls for the travel system, their placement not constituting a part of the invention. The water tank 107, supported at the rear of the main frame 32, supplies water as needed to clean off excess concrete on the parts so that it will not harden during idle periods of the machine. The fuel tank is illustrated at 108 (FIG. 3). The hydraulic oil reservoir can be a specially shaped, flat tank fitted into the frame members 80, 82, 84 and 88-and the cooler therefore is shown at 109. y

The material handling machine of this invention is self-powered, self-steering and self-leveling for fully automatic operation under the control of only one man and can be used for any form of road work or material handling by changing the type of working tool. The features of the suspension control systems and their functions are now described.

The main frame 32 carries the forward outboard support cylinder housing 110 in a vertical position at one corner and the rearward outboard support cylinder 1 12 in a vertical position at the other corner, as two spaced adjustable suspension points for grade control of the main frame and working tool. The support housings 110 and 112 (see FIG. 15) are rigidly attached to the frame by means of the brackets 114 and 116 with suitable diagonal braces 118 and 120 extending to the side member 84. Affixed to an intermediate position on the inboard side of the main frame 32 is a pair of support cylinder housings 122, and 124 for slope control. These cylinders are'spaced fore and aft of the main frame at this suspension point and rigidly supported from the frame by means of the dual bracket 126, the uprights 128 and the angle braces 130 and 132. The supports 122 and 124 house double-acting rams which are connected by means of the pairs of hydraulic hoses 134, 136 and 138 (see FIGS. 1 and 2) to a source of hydraulic power. The flow of hydraulic fluid therein is reversible and controlled by the sensor-actuated valve system described in related US. Pat. No. 3,606,827.

The details of the construction of these supports are shown in said related Patent by an arrangement whereby the dual-acting working cylinders therein are telescopically housed in the outer cylinders 110, 112 and 122 and 124 and are journaled at the top and bottom by clevis pins to provide slight axial resilience and alignment for the workingcylinders during reciprocation and leveling at each suspension point. The working cylinders are attached. through bottom clevis pins to base plates seated in bottoms of the inner cylinders 140 and 142 for the outboard side and the pair of inner cylinders 144 and 145 (FIGS. 3 and 4)'for the inboard side. This arrangement prevents any binding of the parts during reciprocation while the telescoping outer cylinders 110 and inner cylinders 140, for example, maintain a straight line motion.

Referring to FIGS. 1, 4 and 15, the cylinders 140 and, j 1

sion unit and the latter being the rearward suspension unit for the pair of self-propelled crawler type tractor units on that side of the machine. Each of the saddles with its associated cylinder is individually pivotally mounted on a vertical axis from the ends of the cylinder supports 140 and 142 and also reciprocatably controlled by the internal working cylinders. The tractors 150 are pivotally attached on a horizontal axis-to the saddles by means of the saddle pins 152 located substantially in the center of their frame supports 153.

On the inboard side (see FIGS. 2, 4 and 15) the pair of inner guide cylinders 144 and 145 is rigidly mounted to a saddle 154 which is pivotally attached on a horizontal axis intermediate the ends of the walking beam 156 by means of the saddle pin 158 which extends through the saddle mount and the beam forming a central pivot for the walking beam. Also on the inboard sideand at each end ofthe walking beam are attached the inboard tractorunits 150 on their respective saddles 160 (front) and 161 (rear) through saddle pins 152. The arrangement of the tractor units 150 on the outboard and inboard sides of the machine in relation to the main frame 32 is essentially rectilinear, as shown in FIG. 4, with the space 162 (FIG. 4) between the ends of the tractors long enough to provide steering clearance. The wheel base and transverse distance between the tractors can be varied to accommodate different sizes and weights of machinery. Preferably all four tractors are substantially the same length and size so that the ground support is uniform. However, the length of the tractors selected for a given machine can be varied and the space 162 adjusted to accommodate longer wheelbase machines. The vertical steering axes are coincident with the rams on the inboard side'and located at each end of the walking beam 156 on the outboard side and represented by the front and rear pivotal bearing housings 164 (FIG. 15) which receive an upstanding stub axle from the top of each of these saddles.

The arrangement of thelengths of the tractors shown in FIG. 4 in relation to the length Of the frame 32 direction of travel, shown in FIG. 4, is substantiallythesame as the distance, longitudinally of the frame, between the respective pivot or saddle pins 152, so that when placed in tandem the space 162 is as smallas is practical, and provides both steering and pivot clearance. This insures a minimal vertical displacement at the support cylinders for eachcorner of the frame as either end of that tractor is passing'over an obstacle that is higher than the grade, or passingthrough a depression lower tha'nthe grade. For the inboard or t walking beam side any displacement (deviation) at the,

end of a tractor is reduced by one-half of its saddle mount 164 and this displacement is again reduced by one-half by the walking beam and its saddle support.

154 for that side of the frame. On the outboard side each tractor reduces a deviation by about one-half. The tractors each have individual hydraulic drive motors 165 (FIG. 3). These are two-way or reversible hydraulic motors such as Charlyn Orbit motors. The motors on each side are connected in series to each other by .means of suitable hydraulic lines in a manner known in this art.

The space 166 (FIGS. 3, 7 and 8) between the underside of the saddles and the top of, the track of each of the four tractors is sufficient to provide room for the tractors to pivot on their saddle pines 152. In this manner the tractors can negotiate obstacles and unevennesses in the grade 34 that may be in the path of travel, and all of the tractors operate individually so that a correction by one does not affect or require an adjustment by the other.

The steering assembly for the machine of this invention is shown in FIG. 4. The front pair of tractor units is tied together, fore and aft of the saddle pins 152, by means of the paired tie bars 168 and 170. Similarly, the rear pair of crawlers is tied together by the tie bars 172 and 174.,Each tie bar is constructed as an A-frame for rigidity and is mounted to the fore and aft extension plates 175 of the saddles by means of the vertical pivot pins 176 at each end through a suitable journal 206 (see FIGS. 7 and 8). By this arrangement the two fore tractors are turned in unison and the two aft tractors turned in unison. Steering of the front pair of tractors is controlled by the double-acting hydraulic steering ram 177 acting between the pivot pin 178 on the linkage 170 and the pivot pin 180 on the linkage 168. The steering of v the rear tractors is controlled by the ram 182 connected to the linkage 174 by means of the pin 184 and the linkage 172 by means of the pin 186. The hydraulic control hoses for the steering rams 177 and 182 are not indicated for simplicity of illustration. Each of the steering rams is provided with an inlet and outlet hose and is suitably connected to the source of hydraulic pressure in a manner known in the art.

In accordance with one embodiment of this invention the placement of the steering rams 177 and 182 between the pairs of steering linkages instead of between a linkage and the frame or one of the saddle mounts has the distinct advantage of providing a sufficient reduction in the responsiveness of the steering system so that finite control isprovided without oversteer and hunting. The geometry of this arrangement can be changed by reversing the parts by turning the rams end for end or switching their diagonal relationship as by placing either or both of the pins 180 and 186 on the link 170 and 174, respectively and also placing the pins 178 and 184 on the opposite linkages, that is on the links 168 and 172. The spacing of the pivot pins 178 and 180, or 184 and 186 along the links 168 and 170 or 172 and 174 can be varied, as long as the rams 177 and 182 remain on a diagonal in their contracted positions. The extendable lengths of the rams and the amount or degree of steer desired is taken into account, in placing the steering linkages. Normally, a turning angle of about 45 is sufficient foreand aft and in either direction. Normally, the steering geometry fore and aft is the same so that uniform valve action and controlled amounts of steering correction can be applied to these steering rams 177 and 182. The steering action is thereby slowed up uniformly fore and aft, although the ram action is extended further or retracted further in either direction to make a steering correction, so that finite steering control is possible.

In accordance with another embodiment of this invention the respective pairs of steering linkages 168-170 and 172-174 are simultaneously extended or retracted by the same amount as the tractor suspension negotiates uneven grades or the level of the grade on which the two tractors on one side of the machine navigates is lower than or higher than the level of the' grade on which the other pair of fore and aft tractors navigates. This is illustrated in FIG. 4 wherein the link 168 is provided with the double-acting ram 190 between one end and the pivot pin 176 on the saddle 160, while the link 170 has the double-acting ram 192 between its end and the corresponding pivot pin 176 on the same inboard saddle 160. The respective rods 194 and 196 become a part of the steering linkage and each has a piston at its end operating within the ram. The rams 190 and 192 are cross-connected by means of the hydraulic lines 198 and 200 such that the line 198 leads from one side of the piston in ram 190 to the opposite side .of the piston in the ram 192 and the line 200 leads from the other side of the piston in the ram 190 to the opposite side of the piston in the ram 192.

It is apparent that by means of these cross-connect- 1 taneously the other side of the piston in the ram 190 must take in hydraulic fluid, supplied by the line 198 in the direction of the arrow 204. The respective exhaust and intakes of hydraulic fluid by the piston in ram 190 are transmitted to the ram 192 so that its piston can move in the same direction. When the linkages 168 and 170 retract the direction of flow of hydraulic fluid in the lines 198 and 200 is the reverse of the arrows 202 and 204. The lines 198 and 200 have no valves and open cross-connected communication is maintained at all times between the rams 190 and 192, for length compensation.

This relationship is shown in FIGS. 7 and 8 wherein in FIG. 7 the ram l is in a normal or intermediate position on the grade 34 which may also represent a pre-laid and hardened concrete slab. If the machine negotiates a depression or difference in elevation in the grade as shown by the respective grades 34 and 34' in FIG. 8, the tractor unit on that side must lower to maintain the frame and working tool at the desired level or slope. The ram 190 together with the ram 192 (not shown) would extend to allow this action. This relieves any shearing force that may be placed upon the pins 176 and their respective mountings 206 and crossv pins 207 which pivotally tie the linkages to the saddles on two axes. Thissarne change in the length of the linkages 168 and takes place should the change inv 190 and 192 (and 208-210) have equal or substantially equal displacements so that uniform extension and retraction is accomplished although obviously the displacement of one pair need not be the same as the displacement of another pair to accomplish this result. FIGS. 7 and 8 also represent the length extension that the rear linkages 172 and 174 would undergo as the machine negotiates a change in transverse level (slope) along the path of travel on either side of the machine.

' FIG. 3 shows this position of tie bar 174 in broken lines.

FIG. 6 illustrates a further embodiment and modification of the steering and extension linkages just described. The rams used to steer fore and aft need not be connected as shown in FIG. 4 and can be placed in a different position. Here the ram 182 is in the reverse of its position shown in FIG. 4 and the pin 186 is connected at the outboard end of the linkage 172 while the pin 184 is connected on the inboard end of the linkage 174. Also the extension control rams 208 and 210 are now on opposite sides of the machine with their hydraulic lines 212 and 214 extending transversely across and between them in the same manner. This arrangement can be used for the linkages 168 and 170 for the front tractors. Suitable supports (not shown) can be used for the hoses so that they do not hang below the undercarriage.

From the description thus far, it is seen that five saddle mounts are included in the suspension, two (146 and 148) being on the outboard side and three (154,160 and 161) on the inboard side with means to control the level (slope and grade),- direction and horizontal attitude of the machine as it negotiates changes in the grade. The machine travels on the established and prepared grade 34 under the guidance of the grade reference or string line 216 (FIGS. 1 and 3) which is supported from the horizontal arms of suitably spaced posts not illustrated. The string line 216 is placed'outside of the edge of the grade 34,at any desired predetermined elevation in relation to the grade and held by the posts therealong in a manner known in the art to define the path of the working tool. The string line 216 is shown as it may be used to represent the desired level and direction of the curbing 38 to be laid along or upon the edge of the grade 34, as an example.

The machine is accurately guided along the string line 216 by means to detect the direction of the line and by means to detect the elevation of the line. The former variable is detected by the steering sensor 218, for the forward tractors, and the steering sensor 218' for the rear tractors. The latter variable is detected by the elevation sensors 220 and 220' which are mounted for .passage along the string line directly ahead of the respective steering sensors. The steering sensors each have a gimbal-mounted sensing arm 222 which contacts the string line 216 on the machine side thereof, while the elevation sensors have the sensor shoes 224 which contact the underside of the string line 216.

The details of the mounting means for the front sensors 218 and 220 are shown in FIGS. 1 and 12 wherein the pair of spaced uprights 225 and 226 are supported from the mule shoe 30 at or'near the forward plate 40 in a plane transverse the longitudinal axis of the machine and at a point substantially opposite the steering pivot 140. The pair of brackets or plates 227 adjustably attach, by means of the bolts 228, to the respective uprights to hold the tubular member 230 thereacross in a horizontal position. The tubular member 230 has an elongated square bore therein which receives the extensible member 232 in telescopic and non-rotational guided relationship. The end plate 234 is carried in an upright position at the end of the extensible member 232 to which is attached the steering sensor 218. The plate 234 has adjustably affixed thereto the rod 236 of the steering compensator cylinder 238. For this purpose the end of the rod 236 can be threaded to receive a pair of nuts 240,'on each side of the plate 234, only one such nut being shown. The cylinder in turn is suitably supported from the member 230 by means of the pair of brackets 242 suitably spaced therealong. The cylinder 238 and its piston rod can be off-set from the axis of the extensible member 232 or be in line therewith. A pair of hydraulic lines connecting the opposite sides of the piston within the cylinder 238 is illustrated at 244'and 246,the purpose of which will be described The upright members 225 and 226 supporting the forward elevation and steering sensors may be affixed to the frame of the mule shoe or made detachable. In the latter instance, particularly for highway transportation on a trailer, one form of mounting is illustrated by the provision of a tubular section 247 at the end of the longitudinal brace 50 into which the lateral extension 248 of the upright 225 tits in telescoping relationship. A suitable setbolt 250 can be used to fix the upright 225 at the desired position in relation to the steering pivot point 140. A similar arrangement (not shown) would be provided for the upright 226 so that these members can be moved in unison and in the same plane. i

The upright 225 has the cross member 252 affixed at the top thereof and the split ring 254 is affixed at the end of the cross member. The double U-bolt bracket 256 encompasses the split ring so as to slidably engage the grade adjusting jack 258 and provide for fixed attachment at desired elevations. The handle 260 of the jack controls an internal jack screw (not shown) affixed to the L-bracket 262 to accomplish this adjustment. The L-bracket 262 carries the plate 264 having the horizontally oriented slot 266 therein on which the elevation sensor 220 is affixed bymeans of the adjustable guide'pin 268. The sensor shoe 224 is carried by the rod 270 attached to counter-balancing lever 272 which is carried by the pivot pin 274 connected to the sensor 220. The shoe 224 thus rides gently against the underside of the grade reference line 216 and changes in elevation between the pivot pin 270 and the string 216 result in rotationof the pin 270.and activation of the sensor 220. Shoe 224 does not distort the line 216.

The jack screw for the rear elevation sensor 220' is shown at 258, in FIG. 1, with its adjustable mount 256' with the extensions 64 and 66 thereon carrying the bracket plates 227 which hold the tubular member 230'. In both embodiments of these mounts for the steering sensors, and shown in more detail in FIG. 13, i

the pair of bolts 282 extend through the wall of the tubular members and each engages in the slots 284 of the plates 285 which are held by means of the bolts 228. The extensible member 232 and 232 can be angle irons so as not'to interfere with these bolts. The operating rod of the ram 280 is indicated at 281 and is similarly mounted to the extensible member 232'. Thus, the tubular members can be adjusted vertically on the uprights and assembly positioned transversely along the slots 284.

FIG. 14 shows the manner of attachment of the jack 258' for the rear of the machine in which instance the split sleeve bracket 254 with its U-bolt clamps 256 are supported by the rear plate 284 of the frame 68. These parts are interchangeable. The hydraulic'fluid conduits for. the ram 280 at the rear of the machine are shown at 286 and 288.

The relative position of the compensating cylinders 238 and 280 and their hydraulic lines on the inboard side of the machine is shown in FIG. 4. The hydraulic lines 244v and 2460f the cylinder 238 are parallel-connected with a second compensating cylinder 290, the housing of which is pivotally mounted fromthe fixed end of the adjustable bracket 294 carried by the journal or pivot tube 164 at the end of the walking beam. The actuating rod 296 from this cylinder is connected or linked to the front inboard saddle member 160 as at the connection 298. The compensating cylinder 280 is similarly parallel-connected to the second compensating cylinder 300, the housing of which is carried on the pivotal mounting bracket 302, carried in this instance, by the rear saddle 161 on the inboard side. The actuating rod 304 for this cylinder is linked to the fixed arm 306 carried by the journall64 at the rear end ofthe walking beam 156. Parallel connection of the steering sensor compensating cylinders is used with the steering sensors 222 riding on the inside of the string line and the sensors are biased slightly against the string line by a weight or spring so as to be sensitive to any change ,of direction of the machine in relation to the string.

When the front steering sensor arm 222 is moved by the string line 216 and it calls for a correction in the steering or a change in direction, the steering ram 177 is actuated accordingly; and the ram 177 moves to turn right (see FIG. 4) in relation to a direction of travel (arrow 36) for example, the rod 296 is also moved a distance proportional to theamount of steer as the saddle 160 moves in relation to the fixed bracket 294. This causes fluid to exhaust from line 244 into the cylinder 238, and intake of fluid into cylinder 290 via the line 246. The result is that rod 236-is moved outwardly, in the direction of steer, a linear'distance which is equal .to or an increment of the steering correction. This action reduces each steering correction by a fraction so that.

the'total amount of steer is approached in increments by the ram 177 and over steering is reduced. In fact, the steering sensor 218 thereby controls the ram 177 almost. exactly with the corrections imparted to the system by the reference line 216.

The rear steering sensor 218 functions in thesame manner with respect to control of the rear tractors 150 through the steering ram 182; It is to be observed that the steering system, that is rams 177 and 182, with their double linkages, or the bars, fore and aft of the vertical pivot points 140142 on the outboard side and similarly spaced on the inboard side, cooperate with each other to control the direction of the machine. In

the foregoing example where a right turn of the front tractors was described, this maneuver will also tend to twist or pivot the rear tractors to the right. This movement will cause the rear steering sensor arm 222 to move away from the string line 216 and call for a correction in the steering in the same direction but a lesser amount. If the machine is actually approaching a right hand curve, the rear sensor may in the next few feet'of travel move closer to the string line as the front tractors start to follow the curve. This will result in a compensating left hand turning correction for the rear tractors until they also approach the right hand curve. The hydraulic lines 244, 246, 286 and 288 being flexible do not interfere with the slope compensating lengthening or shortening of the cylinders or rams 190, 192 or 208 and 210. V

In another embodiment of this invention the machine 5 is adapted to a rearrangement of the parts to reduce its width to about 8 feet for transportation under its own power or for highway travel, as on a trailer. The power and hydraulic system of the machine is utilized .to facilitate this re-arrangement. The screw conveyor 18 and the hopper 12 are formedas a unit construction and welded together at their juncture 307 (FIG. 1). The front cross frame member is provided with the cleat 308 (FIG.15) having the bore hole 309 and a depending bracket 310 from which the support pin 312 extends. The back'corner of the hopper has the upright pin 313 (FIG. 21). The screw conveyor 18 has a pair of spaced cleats 314 with aligned bores to receive the pin,

312. A nut 316 holds the assembly together with the pin 312 forming a pivotal axis for the conveyor and hopper unit. The bracket 318 has the arcuate flattened edge 320 which encompasses under the rounded. housing of the conveyor 18 in the manner'shown in FIG. 1. The frame carries the upright stanchion member 322 having the bracket 324 at the top end to support the pulley 326. The discharge end ofthe conveyor has the eye member'328 to which the cable 330 is attached. The cable 330'passes through the pulley 326 and the bight end 330' is temporarily attachedto a notch 331 (FIG. 21 in a lower'weir of the conveyor so that the assembly can be raised from the position of rest on the bracket 318, with the pin 313 engaged in the clear 308,

(FIGS. 1 and 17 to the travel position shown in FIGS.

18 and 19 by operating the conveyor to wind up the cable between the weirs of the conveyor helix or on the, end portion of the supporting shaft. The outside edge of the hopper is no wider than the inboard tractors in the travel position. The center of gravity of the hopperconveyor unit is on the outboard side of the pivot'pin 312 so that this unit when empty or filled, normally rests upon the bracket support 3l8. The pin 313 and chat 308 merely provide additional stability to the as- This frame also serves as the support for the tanks 107 and 108, previously described. FIG. 20 shows in detail a form of mounting that is used to attach the mule shoe to the rear of the machine. As illustrated the bracket 334 has a pair of bore holes 336 which match with the I bore holes 338 of the bracket 76 to receive bolts to attach these parts together.-The square edge 340 abuts against the flange 342 in this attachment to bracket 76. The bracket 72 attaches to the inboard bracket 332 in the same manner. The machine is then raised on its four rams and run upon a trailer under its own power.

FIGS. 9, and 11 illustrate another embodiment of the invention in which the mule shoe 30 has been modified to provide the vertically slidable apron plate 340, the lower edge 342 of which extends longitudinally of the side of the mule shoe. This plate is v slidably mounted on a vertical axis by means of the support 344 which is carried by the mule shoe frame and also carries the double acting ram 346, the piston thereof is illustrated at 348 by broken lines. The rod 350 extends to the journal 352 that is pivotally attached to the pin 354 carried by the guide plate 356. The guide plate is attached to the pair of U-shaped brackets 358 as at the weldments 360 and the ends of the brackets are welded to the apron plate 340 as at 362. This provides a space 364 between the guide plate 356 and the mule shoe 30 to receive the vertical T-beam 366 supported at the. end of the horizontal support 370 carried by the top of the mule shoe. The juncture of the bottom bracket 358 and the plate 356 has the brace member 372 welded therein to which is attached the journal 374. The actuating rod 376 is carried within the journal 374. The journal has a pair of bearing gland members 377 and 378 which slidably receive the rod 376 in sealed relationship.

The hydraulic line 382, from a source of hydraulic pressure, leads to the valve member 384 carried at the top of the support sleeve 386 throughwhich the rod 376 extends in operative reciprocating relationship with the valve. The support sleeve extends from the adjusting nut 388 which engages the internal threads in the lower gland member 377 and also encompasses the rod 376 in slidable relationship. The pair of hydraulic lines 389 from the valve 384 are connected to respective sides of the piston 348 in the ram 346. The rod 376 is pivotally mounted from the pin 387 at its bottom end to suitable spaced cleats extending from the sensing ski 390 having the upturned front end 392. The ski 390 is adapted to slide along the grade surface and detect macro deviations of the grade along the side of the mule shoe into which concrete may spill and be wasted. When the ski 390 detects such a depression, for example, it lowers and actuates the valve 384 to open same and move the piston 348 downwardly. This moves the apron plate 340' downward along the T-beam 366, guided by the plate 356. The end 394 of the T-beam 366 is unsupported for easy detachment of the assembly and to allow the apron plate 340 to extend therebelow. The plate 356 rides against the T-beam 366 at the sliding juncture 396 as the back flat side 398 of the T-beam 366 rides against the apron plate 340. The apron plate 340 is held in spaced relationship with the mule shoe 30 as indicated at 400. Since the apron plate 340 is pivotally mounted on the pin 354, it can also swing to either side within the limits of the space 364 about the T-beam 366. More than one such apron plate 340 can be used along the outside of the mule shoe although in practice this arrangement is only necessary at or immediately to therear of the support 48 where the greatest compression and vibration forces are acting on the concrete and the tendency to squeeze v out into any depressions thatmay be encountered along the grade without disturbing the attitudev of the mule shoe. The apron plate 340 can be as long as is necessary to accomplish this purpose and more than one apron plate and actuating ski can be used alongside of the mule shoe. Alternatively, a single elongated apron plate can be used with a single elongated ski member each of which is supported at the ends as shown in FIGS. 9, l0 and 11.

FlG.l6 illustrates in partial diagrammatic form an alternative arrangement with the same reference numbers used for the parts. The pair of supporting rams 122 and 124 is mounted central of one end of the frame and the extensible members thereof are attached to the saddle member 154 on each side of the saddle pin 158 which attaches through the walking beam at its center. The tractors 150 are carried by the saddles 161 and 164 at the ends of the walking beam as before described. At the other end of the frame 32 and at each corner the supporting rams and 112 are suitably mounted and their extensible members carrythe saddles 146 and 148, respectively, with the second pair of tractors therein. The steering linkages (not shown) for this arrangement would be the same as previously described and would be connected transverse the frame 32 between the pairs of tractors. In this embodiment, the working tool can been either side of the frame or located central of the frame. Either'end of the machine shown in FIG. 16 can be considered to be the front and the width of the frame can be less than, equal to or greater'than the length, as desired. The rams 1 10 and 112 can control the slope. The double rams 122-124 work in unison as in the embodiment of FIG. 1 and can control the grade with or without the cooperation of the rams 110 and 112 operated in unison.

With the suspension, steering and compensating controls of this invention incorporated in a machine to lay concrete curbing, a work range of about 10 to 28 feet tractors may be stopped or the opposite pair reversed although this type of steering is not employed while a curb is being laid. An advantage of the travel and steering system is that steering by crabbing is unnecessary to control the machine during the performance of work thereby and the hydraulic system is maintained at equilibrium or substantially so during most of the operation time. Pressure gauges are included in the hydraulic system to make it possible to balance the various rams and maintain equilibrium conditions particularly when the machine is negotiating a smooth radii in a cul-de-sac.

The slope control system employs a servo-valve, such as the Honeywell V 7059A, which is capable of controlling the flow direction and rate of flow to values proportional to the signal received, for the pair of support rams 122 and 124 on the inboard side. The ram supports 110 and 112 are individually controlled by the elevation sensors 220 and 220', through servo valves.

The rams 122 and 124 are connected to be actuated in unison with a common hydraulic conduit connected to the underside of the pistons and a common hydraulic conduit connected to the top side of the pistons. The signal for the servo valves for the rams 122 and 124 is supplied by a suitable pendulumoperated device, such as that disclosed in said copending application or the Honeywell model W 894A proportional slope controller. This latter instrument operates on 12 V.D.C. and employs an integral gravity-sensitive pendulum to sense changes in slope and provide a proportional output to correct for deviation from a set point, through a special high resolution microsyn transducer. The slope detector can be located anywhere on the machine and is preferably on the console as indicated at 402 with a remote set unit 404 also on the console which is capable of setting the percentage and direction of slope from percent to -l0 percent in 0.00] percent increments. The slope control 402 has a gain control knob and a meter which shows the amplitude and phase of voltage being applied to the servo valve.

In setting up the front elevation sensor 220 minor adjustments of the shoe 224 in relation to the string line 216 are made by the jack 258 by turning the handle 260. Lowering the sensor raises the machine and raising the sensor lowers the machine. The guide line 216 can be set level withthe top of the curb grade or up to about 2 feet above the curb level. A slight taper upwards of about 1 inch above the finished grade may be maintained on the mule-shoe and be advantageous for some types of work.

Tapering of the longitudinal attitude of the mule shoe aids in getting the correct action in the finished product and the amount of taper is dependent on the type of curb. Sensitivity adjustments (gain) are accomplished by adjustment of the remote set unit on the console. This gain adjustment retards hunting in the system. Over-sensitivity may create erratic elevation response while under-sensitivity creates a lag in the response.

Adjustment of the rear elevation sensor 218' is of importance to establish the final grade of the finished product. The initial adjustment should be such that the top of the mule shoe 30 is level withthe top of the curb grade and the sensors are adjusted in small increments by means of the jacks so that the finished curb is on grade.

The front and rear steering compensator rams 238, 290 and 280, 300 are pre-loaded with hydraulic oil at about 600 psi. Check valves are mounted on the front I and rear ports of the cylinders, such as 238 to recharge the parallel system from a charging gun with hydraulic oil to maintain this pressure and avoid springiness of the rams. The tie rod compensators 190-192 and 208-210 are connected in a closed circuit reverse port configuration to allow the tie rods to telescope without distorting the track alignment. This system namely cross-connected cylinders 190, 192,

208 and 210 may require periodic re-charging and is maintained at 1000 psi. When these compensators are properly charged the tracks should be parallel.

In preparing the machine for transport the sensors will be removed. A safety chain can be employed to hold the conveyor 18 (auger) and hopper l2 assembly g in the raised position. The auger weir can be used to wind up the cable 330 at the top end or mid-portion of the conveyor using the stanchion 322 as the fixed point, of the cable. The channel 50 can be at the bottom edge of the mule shoe 30 or spaced thereabove. The mule shoe can have a gradually smaller cross sectional open ing toward the rear or discharge end to aid in compaction of the concrete.

The hydraulic connections for the compensating cylinders 238-290 and 280-300 have been described in relation to steering sensors placed to act upon the inside of the grade line 216. If the steering sensors are located so as to pass along the outside of the grade line, the hydraulic connections at one of each of these pairs of compensating cylinders would be reversed. For example the-line 244 would connect to the rod side of the piston in the cylinder 238 and the line 286 would connect to the rod side of the piston in cylinder 280, with the connections on the inboard side remaining the same, with the front steering sensor 222 on the outside of the grade line 216. As already stated the rear steering sensor 218 is preferably ator near the pivot point 142 or at the rear end of the mule shoe and the front steering sensor 218 is preferably fore or-aft of the front pivot point 140. The manner in which the cylinders 290 and 300 are mounted, in FIG. 4, to the respective pivot tubes and saddle would be reversed if they were,

respectively, behind the front pivot point 164 and in front of the rear pivot point (or pivot tube) 164. Thus, if the rear sensor were located in front of the pivot 142 and in front of the rear pivot tube 164, the cylinder 300 would be mounted like the cylinder 290, that is, in a fixed position with the rod 304 extended and retracted by the saddle 161. Other arrangements for obtaining these relative movements of the parts will become apparent to one-skilled in the art. Also, other adjustments can be incorporated into the suspension of the mule shoe, such as turnbuckles fore and aft to control the taper aboveelevation at the front and means can be inwhich the curb is laid can be graded to one-fourth to one-half inch below the grade on which the machine travels to assure that the mule shoe will not strike on high material and cause inaccurate final grade of the finished product. The foregoing limitations do not apply to the same extent for larger material handling machines.

From the foregoing description it is apparent that the suspension arrangement described herein, with auto- 1 matic control of grade and slope of the mainframe can also be applied to the working tool alone. In the embodiment of FIGS. 1 and 2, the actuating means 220, connected to the pair of extensible members 110 and 112, would be operative for engagement with the grade reference 216 to control the grade of the main frame 32. The actuating means for the pair of extensible members 122 and 124 would be operative through a gravity operated pendulum, a separate slope control line or a gauge wheel to extend and retract these members in unison to control the slope. Also the suspension and steering arrangement with automatic control of the steering, grade and slope of the main frame, as applied to the embodiment shown in FIGS. 1 and 2, is applicable to the embodiment disclosed in FIG. 16 using the automatic electrical and hydraulic system disclosed in said copending application. The grade deviation compensating extensible members in the steering linkage, not disclosed in FIG. 16, are particularly applicable to the pair of tractors suspended from the saddle mounts 146 and 148 and may also be used for the steering linkages ofthe tractors suspendedfrom the walking beam since these extensible members 190-192 also serve the function of controlling the toe-in of the tractors.

The suspension of FIG. 16 is particularly versatile in grade and slope control. It is apparent that grade control of the frame 32 in the embodiment of FIG. 16 can be obtained by operating the extensible members 110 and 112 in unison or the extensible members 122 and 124 in unison or a combination of these functions, using actuating means operative for engagement with the grade reference line. Slope control for this embodiment would be obtained by operating one or the other of the extensible members 110 or 112 individually. In the alternative, the extensible member 110 can be used for grade control in conjunction with the pair of extensible members 122 and 124 and the extensible member 112 used for slope control alone. If the working tool is in the middle of the frame 32 all of the extensible members or rams can be used to control the attitude of the frame in other combinations.The advantages of sensitive steering control gained by using the oblique steering linkage means 177 and 182 would apply to the steering of the paired tractors shown in FIG. 16. The machine shown in FIG. 16 can be operated with the walking beam at the front or rear end in relation to the direction of travel.

What is claimed is: v

1. A material handling machine comprising: a

a mainframe supported through adjustable suspension means upon frontand rear ground engaging means to accommodate transportation thereof;

a pair of said ground engaging means being on opposite sides of said main frame and each being pivotally mounted on a vertical axis;

spaced substantially parallel transverse steering linkage means pivotally connected fore and aft of the said transverse steering linkage means to turn said ground engaging means about their respective vertical axes in unison; and

said spaced steering linkage means including extensible members operative to extend and retract in unison to compensate for changes in slope between said pair of ground engaging means.

2. A material handling machine in accordance with claim 1 in which said machine includes;

front and rear opposite pairs of said ground engaging means connected to each other by said spaced steering linkage means; I

a linkage member pivotally connected between transversely spaced points of the respective, transverse steering linkage means for each pair of said ground engaging means; and

actuating means for said respective linkage members operative to independently turn said pairs of posite the fore piv'ot connecting of its steering link age means; and said sensor means for said rear pair of ground engaging means being disposed substantially opposite the rear pivot connection of its steering linkage. 4. A material handling machine in accordancewith claim 1- including:

actuating means for said adjustable suspension means operative to maintain said main frame in a predetermined plane; and actuating means for said linkage member controlling said transverse steering linkage means to turn said pair of ground engaging means about their respective pivotal axes in unison. 5. A material handling machine in accordance with claim 1 in which:

said extensible members for each of said spaced steering linkage means comprise balanced fluidoperated cylinders connected so as to extend and retract in unison. 6. A material handling machine in accordance with claim 1 including: a

sensor means for said pair of ground engaging means operative to engage a grade reference controlling the direction of steer of said machine along a path of travel; said sensor means being disposed substantially-opposite the fore pivot connection of one of said steering linkage means. 7. A material handling machine in accordance with claim 2 in which:

ground engaging means about their respective vergaging means being disposed substantially opone of the front ground engaging means and one of the rear ground engaging means on the same side 1 of said main frame are provided with individual suspension means;

the other side of said main frame is provided with a I walking beam extending longitudinally thereof;

said walking beam is pivotally mounted on a transverse axis to an adjustable suspension means;

the remaining front and rear ground engaging means on said other side of said main frame being pivotally mounted at the ends of said walking beam.

8. A material handling machine in accordance with claim 2 in which:

one of the rear ground engaging means on one side of said main frame and one of the rear ground engaging means on the other side of the main frame are provided with individual suspension means;

an adjustable suspension means is provided for said main frame forward of said rear pair of ground engaging means; 1

a walking beam pivotally mounted on a longitudinal axis from said adjustable suspension means; and

the remaining front ground engaging means being pivotally mounted at the ends of said walking beam.

9. A material handling machine in accordance with claim 3 in which:

said sensor means for said front and rear pair of ground engaging means are disposed on the same side of said'main frame for operative engagement with the inside of a guide reference controlling the direction of steer of said machine along a path of travel;

a first hydraulic means having an extensible member and a fixed cylinder member is provided for saidv front ground engaging means on the side opposite the front sensor means;

said extensible member of said first hydraulic means being connected to and responsive to the pivotal turning of said front ground engaging means;'and

a second hydraulic extensible means parallel con nected to said first hydraulic extensible means and supporting said front sensor means, whereby actuation of said first hydraulic extensible means in a steering correction causes said second hydraulic extensible means to move in the same direction and an incremental amount of said steering correction of the front pair of ground engaging means;

a third hydraulic extensible means having a fixed extensible member and a movable cylinder is provided for said rear ground engaging means on the side opposite the rear sensor means;

said movable cylinder of said third hydraulic means being connected to and responsive to the pivotal turning of said rear ground engaging means;

a fourth hydraulic extensible means parallel connected to said third hydraulic extensible means and supporting said rear sensor means, whereby actuation of said third hydraulic extensible means in a steering connection causes said fourth hydraulic extensible means to move in the same direction and an incremental amount of said steering connection of the rear pair of ground engaging means while maintaining said front and rear steering sensors in substantial contact with the inside of said grade referencev 10. A material handling machine in accordance with claim 1 in which:

said extensible members comprise hydraulicallyoperated dual-action cylinders having a closed circuit hydraulic system wherein the opposite sides of said cylinders are connected so that the exhaust from one becomes the intake of the other and the intake of said one becomes the exhaust of the other.

1 l. A material handling machine in accordance with claim 1 adapted to follow an external guide reference disposed along the path of travel including:

a first hydraulic extensible member responsive to the pivotal turning of one of said ground engaging means in said pair;

a second hydraulic extensible member connected to said first hydraulic extensible member;

said second extensible member carrying a direction sensor adapted to follow said guide reference,

,whereby actuation of said first extensible member in a steering correction causes said second extensible member to move in the same direction and in an incrementalamount of said steering correction.

12. A material handling machine in accordance with claim ll in which:

said direction sensor is adapted to contact the inside of said grade reference in relation to said machine and said first and second extensible members are parallel connected. j

13. A material handling machine comprising:

a main frame;

a working tool supported by said main frame for ground engagement; l

a pair of extensible suspension members disposed in spaced substantially vertical relationship from one side of said main frame from and rear of said machine;

said extensible suspension members respectively supporting said frame upon front and rear pivotally mounted ground engaging means; a pair of extensible suspension members disposed in adjacent substantially vertical relationship from the other side of said main frame; a walking beam pivotally disposed from an axis under the adjacent extensible members and extending along the other side of said machine; a pair of pivotally mounted front and rear ground engaging means disposed from said walking beam ground engaging means on opposite sides of said main frame;

each of said steering linkage means in a pair for the front and rear opposite pairs of ground engaging means including a compensating cylinder operative to extend and retract the effective length thereof, said compensating cylinders for each pair of steering linkage means being connected so as to extend and retract in unison to compensate for changes in slope between said pairs of ground engaging means;

extensible linkage members pivotally connected to each pair of said steering linkage means; and

actuating means for each of said extensible linkage members to independently turn said ground engaging means about their respective pivotal axes in unison.

14. A material handling machine in accordance with claim 13 in which: 7

the compensating cylinder for one of said steering linkage means in a pair of connected at one end thereof; and

the compensating cylinder for the other of said steering linkage means is connected at the opposite end thereof. v

15. A material handling machine in accordance with claim 13 including:

sensor means for said respective front and rear ground engaging means adapted for operative engagement with a guide reference controlling the direction of steer of said machine along a path of travel and being operative to actuate said respective pivotally mounted linkage members;

a compensating cylinder reciprocatably supporting each of said sensor means;

a second compensating cylinder pivotally connected to and actuated by one of said pairs of ground engaging means; and

said compensating cylinders for each pair of ground engaging means being connected so as to extend and retract in a direction and linear amount equal to an increment of a steering connection.

16. A material handling machine in accordance with claim 15 including:

a bracket member reciprocatably supporting said sensor means andsaid compensating cylinder for transverse adjustment in relation to said main frame.

17 A material handling machine in accordance with claim 13 in which:

said working tool is adapted for support longitudinally ofa side of said main frame;

support means for said working tool adapted to extend and retract said working tool in relation to said main frame; and

a second support means on an adjacent side of said main frame whereby said working tool is adapted to be relocated for highway travel.

18. A material handling machine in accordance with claim 17 including:

a material handling system comprising a receiving hopper for said material and a conveyor for elevating said material;

a second hopper to receive said material from said conveyor for deposit and compaction by said working tool;

19.A material handling machine in accordance with claim 13 in which:

the extensible compensating members are hydraulic cylinders having a closed circuit hydraulic system wherein the opposite sides of said cylinders are connected so that the exhaust from one'becomes the intake of the other and the intake of said one becomes the exhaust of the other. 20. A material handling machine in accordance with claim 18 in which:

said conveyor comprises an elongated helical member having weirs rotatably mounted within an open-sided housing; means to drive said helical member; and cable means are provided for attachment between said machine and said helical weir to wind thereon whereby said material handling system is pivotable to travel position. I v 21. A material handling machine in accordance with claim 13 in which: said working tool comprises a slip form for laying a continuous concrete layer;

said slip form includes a frame having spaced bracket membersadapted for attachment to said bracket members whereby said slip form is positionable in extended relationship from the side of said main I frame.

22. A material handling machine in accordance with claim 13 in which:

said extensible linkage members are connected obliquely between transversely spaced points of said steering linkage means of each pair thereof.

23. A material handling machine comprising:

a main frame; 7

a working tool supported by said main frame for ground engagement; Q

a pair of extensible suspension members disposed in spaced substantial vertical relationship on opposite sides of said main frame;

.said extensiblesuspension members respectively supporting one end of said frame upon pivotally mounted ground engagement means;

a second pair of extensible suspension members disposed in adjacent substantially vertical relationship at another end of said main frame;

a walking beam pivotally disposed from an axis between said second pair. of extensible members and extending transverse said other end of said main frame;

a pair of pivotally mounted ground engaging means disposed in spaced relationship from said walking beam;

means to individually drive each of said ground engaging means;

steering linkage means connected fore and aft of the respective pivotal axes and transversely of the ground engagement means at both ends of said main frame; 

1. A material handling machine comprising: a main frame supported through adjustable suspension means upon front and rear ground engaging means to accommodate transportation thereof; a pair of said ground engaging means being on opposite sides of said main frame and each being pivotally mounted on a vertical axis; spaced substantially parallel transverse steering linkage means pivotally connected fore and aft of the respective pivotal axes of said opposite pair of said ground engaging means; a linkage member operatively connected to one of said transverse steering linkage means to turn said ground engaging means about their respective vertical axes in unison; and said spaced steering linkage means including extensible members operative to extend and retract in unison to compensate for changes in slope between said pair of ground engaging means.
 2. A material handling machine in accordance with claim 1 in which said machine includes; front and rear opposite pairs of said ground engaging means connected to each other by said spaced steering linkage means; a linkage member pivotally connected between transversely spaced points of the respective transverse steering linkage means for each pair of said ground engaging means; and actuating means for said respective linkage members operative to independently turn said pairs of ground engaging means about their respective vertical axes in unison and in either direction.
 3. A material handling machine in accordance with claim 2 including: sensor means for said respective front and rear pairs of ground engaging means adapted for operative engagement with a guide reference controlling the direction of steer of said machine along a path of travel; said sensor means for said front pair of ground engaging means being disposed substantially opposite the fore pivot connecting of its steering linkage means; and said sensor means for said rear pair of ground engaging means being disposed substantially opposite the rear pivot connection of its steering linkage.
 4. A material handling machine in accordance with claim 1 including: actuating means for said adjustable suspension means operative to maintain said main frame in a predetermined plane; and actuating means for said linkage member controlling said transverse steering linkage means to turn said pair of ground engaging means about their respective pivotal axes in unison.
 5. A material handling machine in accordance with claim 1 in which: said extensible members for each of said spaced steering linkage means comprise balanced fluid-operated cylinders connected so as to extend and retract in unison.
 6. A material handling machine in accordance with claim 1 including: sensor means for said pair of ground engaging means operative to engage a grade reference controlling the direction of steer of said machine along a path of travel; said sensor means being disposed substantially opposite the fore pivot connection of one of said steering linkage means.
 7. A material handling machine in accordance with claim 2 in which: one of the front ground engaging means and one of the rear ground engaging means on the same side of said main frame are provided with individual suspension means; the other side of said main frame is provided with a walking beam extending longitudinally thereof; said walking beam is pivotally mounted on a transverse axis to an adjustable suspension means; the remaining front and rear ground engaging means on said other side of said main frame being pivotally mounted at the ends of said walking beam.
 8. A material handling machine in accordance with claim 2 in which: one of the rear ground engaging means on one side of said main frame and one of the rear ground engaging means on the other side of the main frame are provided with individual suspension means; an adjustable suspension means is provided for said main frame forward of said rear pair of ground engaging means; a walking beam pivotally mounted on a longitudinal axis from said adjustable suspension means; and the remaining front ground engaging means being pivotally mounted at the ends of said walking beam.
 9. A material handling machine in accordance with claim 3 in which: said sensor means for said front and rear pair of ground engaging means are disposed on the same side of said main frame for operative engagement with the inside of a guide reference controlling the direction of steer of said machine along a path of travel; a first hydraulic means having an extensible member and a fixed cylinder member is provided for said front ground engaging means on the side opposite the front sensor means; said extensible member of said first hydraulic means being connected to and responsive to the pivotal turning of said front ground engaging means; and a second hydraulic extensible means parallel connected to said first hydraulic extensible means and supporting said front sensor means, whereby actuation of said first hydraulic extensible means in a steering correction causes said second hydraulic extensible means to move in the same direction and an incremental amount of said steering correction of the front pair of ground engaging means; a third hydraulic extensible means having a fixed extensible member and a movable cylinder is provided for said rear ground engaging means on the side opposite the rear sensor means; said movable cylinder of said third hydraulic means being connected to and responsive to the pivotal turning of said rear ground engaging means; a fourth hydraulic extensible means parallel connected to said third hydraulic extensible means and supporting said rear sensor means, whereby actuation of said third hydraulic extensible means in a steering connection causes said fourth hydraulic extensible means to move in the same direction and an incremental amount of said steering connection of the rear pair of ground engaging means while maintaining said front and rear steering sensors in substantial contact with The inside of said grade reference.
 10. A material handling machine in accordance with claim 1 in which: said extensible members comprise hydraulically-operated dual-action cylinders having a closed circuit hydraulic system wherein the opposite sides of said cylinders are connected so that the exhaust from one becomes the intake of the other and the intake of said one becomes the exhaust of the other.
 11. A material handling machine in accordance with claim 1 adapted to follow an external guide reference disposed along the path of travel including: a first hydraulic extensible member responsive to the pivotal turning of one of said ground engaging means in said pair; a second hydraulic extensible member connected to said first hydraulic extensible member; said second extensible member carrying a direction sensor adapted to follow said guide reference, whereby actuation of said first extensible member in a steering correction causes said second extensible member to move in the same direction and in an incremental amount of said steering correction.
 12. A material handling machine in accordance with claim 11 in which: said direction sensor is adapted to contact the inside of said grade reference in relation to said machine and said first and second extensible members are parallel connected.
 13. A material handling machine comprising: a main frame; a working tool supported by said main frame for ground engagement; a pair of extensible suspension members disposed in spaced substantially vertical relationship from one side of said main frame front and rear of said machine; said extensible suspension members respectively supporting said frame upon front and rear pivotally mounted ground engaging means; a pair of extensible suspension members disposed in adjacent substantially vertical relationship from the other side of said main frame; a walking beam pivotally disposed from an axis under the adjacent extensible members and extending along the other side of said machine; a pair of pivotally mounted front and rear ground engaging means disposed from said walking beam and supporting said main frame thereon; means to individually drive each of said ground engaging means on the same side of said main frame at the same speeds; a pair of spaced substantially parallel transverse steering linkage means pivotally connected fore and aft of the respective pivotal axes of the front ground engaging means on opposite sides of said main frame; a pair of spaced substantially parallel transverse steering linkage means pivotally connected fore and aft of the respective pivotal axes of the rear ground engaging means on opposite sides of said main frame; each of said steering linkage means in a pair for the front and rear opposite pairs of ground engaging means including a compensating cylinder operative to extend and retract the effective length thereof, said compensating cylinders for each pair of steering linkage means being connected so as to extend and retract in unison to compensate for changes in slope between said pairs of ground engaging means; extensible linkage members pivotally connected to each pair of said steering linkage means; and actuating means for each of said extensible linkage members to independently turn said ground engaging means about their respective pivotal axes in unison.
 14. A material handling machine in accordance with claim 13 in which: the compensating cylinder for one of said steering linkage means in a pair of connected at one end thereof; and the compensating cylinder for the other of said steering linkage means is connected at the opposite end thereof.
 15. A material handling machine in accordance with claim 13 including: sensor means for said respective front and rear ground engaging means adapted for operative engagement with a guide reference controlling the direction of steer of said machine along a path of travel and being operative to aCtuate said respective pivotally mounted linkage members; a compensating cylinder reciprocatably supporting each of said sensor means; a second compensating cylinder pivotally connected to and actuated by one of said pairs of ground engaging means; and said compensating cylinders for each pair of ground engaging means being connected so as to extend and retract in a direction and linear amount equal to an increment of a steering connection.
 16. A material handling machine in accordance with claim 15 including: a bracket member reciprocatably supporting said sensor means and said compensating cylinder for transverse adjustment in relation to said main frame.
 17. A material handling machine in accordance with claim 13 in which: said working tool is adapted for support longitudinally of a side of said main frame; support means for said working tool adapted to extend and retract said working tool in relation to said main frame; and a second support means on an adjacent side of said main frame whereby said working tool is adapted to be relocated for highway travel.
 18. A material handling machine in accordance with claim 17 including: a material handling system comprising a receiving hopper for said material and a conveyor for elevating said material; a second hopper to receive said material from said conveyor for deposit and compaction by said working tool; said receiving hopper and said conveyor being pivotally mounted from a common axis from said main frame whereby with said working tool attached to said second support means said receiving hopper and conveyor are pivotable to a position no wider than said main frame for highway travel.
 19. A material handling machine in accordance with claim 13 in which: the extensible compensating members are hydraulic cylinders having a closed circuit hydraulic system wherein the opposite sides of said cylinders are connected so that the exhaust from one becomes the intake of the other and the intake of said one becomes the exhaust of the other.
 20. A material handling machine in accordance with claim 18 in which: said conveyor comprises an elongated helical member having weirs rotatably mounted within an open-sided housing; means to drive said helical member; and cable means are provided for attachment between said machine and said helical weir to wind thereon whereby said material handling system is pivotable to travel position.
 21. A material handling machine in accordance with claim 13 in which: said working tool comprises a slip form for laying a continuous concrete layer; said slip form includes a frame having spaced bracket members along one side; and said main frame includes spaced telescoping side members adapted for attachment to said bracket members whereby said slip form is positionable in extended relationship from the side of said main frame.
 22. A material handling machine in accordance with claim 13 in which: said extensible linkage members are connected obliquely between transversely spaced points of said steering linkage means of each pair thereof.
 23. A material handling machine comprising: a main frame; a working tool supported by said main frame for ground engagement; a pair of extensible suspension members disposed in spaced substantial vertical relationship on opposite sides of said main frame; said extensible suspension members respectively supporting one end of said frame upon pivotally mounted ground engagement means; a second pair of extensible suspension members disposed in adjacent substantially vertical relationship at another end of said main frame; a walking beam pivotally disposed from an axis between said second pair of extensible members and extending transverse said other end of said main frame; a pair of pivotally mounted ground engaging means disposed in spaced relationship from said walking beam; means to individually drive each of said ground eNgaging means; steering linkage means connected fore and aft of the respective pivotal axes and transversely of the ground engagement means at both ends of said main frame; extensible linkage members pivotally connected obliquely between each of said fore and aft steering linkage means on opposite sides of said pivotal axes; actuating means for said oblique extensible members to turn said ground engaging means about their pivotal axes in unison; and one pair of said steering linkage means each including an extensible compensating member; said compensating members being connected so as to extend and retract in unison; actuating means connected to said pair of extensible suspension members for operative engagement to control the transverse slope of said main frame; and actuating means for said second pair of extensible suspension members for operative engagement with a grade reference to extend and retract same in unison to control the grade of said main frame.
 24. A material handling machine adapted to deposit formable material along a path of travel comprising, a main frame supported through adjustable suspension means upon ground engaging means to accommodate transportation thereof, a pair of said ground engaging means being on opposite sides of said main frame and each being pivotally mounted on a vertical axis, a slip form attached to one side of said main frame and extending therealong, hopper means carried by said main frame between said pair of ground engaging means to supply said slip form with formable material, steering linkage means extending transverse said main frame and pivotally connected to said pair of ground engaging means forward of said vertical pivotal axes, sensor means for said pair of ground engaging means operative to engage a grade reference controlling the direction of steer of said machine along said path of travel said sensor means being disposed on said one side of said main frame ahead of said slip form, forward of said vertical axes of said pair of ground engaging means and substantially opposite the pivotal connection of said steering linkage means and means supporting said sensor means operative to move said sensor means in the same direction and in a linear incremental amount of a steering correction. 